The powerful bomb ripped through a bazaar in Hazara Town, an area dominated by Shiites on the outskirts of Quetta, the capital of Balochistan province, on Saturday night.

''We have recovered more dead bodies from the debris of a collapsed building,'' a senior Quetta police officer, Wazir Khan Nasir, said on Sunday.

The Chief of Police of Quetta, Zubair Mehmood, said the bomb was hidden in a water tank that was towed to the market by a tractor. The water tank, packed with about 800 kilograms of explosives, was near a pillar of a two-storey building, which collapsed in the blast.

Mr Nasir said the bombing was a sectarian attack and the Shiite community was the target.

A spokesman for the banned Sunni extremist group Lashkar-e-Jhangvi claimed responsibility for the attack.

Officials and witnesses said an angry mob initially surrounded the area after the bombing and prevented police and rescue workers from reaching the site.

''They were angry and started a protest, some of them pelted police with stones,'' the province's Home Secretary, Akbar Hussain Durrani, said, adding that authorities and medical personnel were eventually given access.

The spokesman for Shiite groups in the area, Syed Qamar Haider Zaidi, condemned the Pakistani government for not protecting the community.

On Sunday morning, the city was shut down by a strike called by the Hazara Democratic Party to honour the dead and protest against the slaughter.

Shiites in Pakistan have been increasingly attacked by militant Sunni groups who view them as heretics and non-Muslims. Shiites account for about a fifth of the country's 180 million people.